Fluid injectors are well known for injecting a fluid into an atmosphere. One well known type of fluid injector is used to inject a reagent such as liquid urea, also known as Diesel Exhaust Fluid (DEF), into an exhaust stream of an internal combustion engine for use in a selective catalytic reduction (SCR) exhaust aftertreatment process. A second well known type of fluid injector is used to inject fuel, such as gasoline or diesel fuel, into an internal combustion engine. In the case of the fluid injector which is used to inject liquid urea, it is important for the liquid urea to be atomized as finely as possible to promote the exhaust aftertreatment process. In the case of the fluid injector which is used to inject fuel, it is important for the fuel to be atomized as finely as possible in order to promote efficient combustion.
Fluid injectors generally include a valve seat with an aperture extending therethrough. A complementary valve member is selectively seated and unseated with the valve seat in order to prevent and permit fluid flow respectively through the aperture. In order to promote atomization, it is known to provide a director plate downstream of the valve seat. The director plate includes one or more director plate apertures extending therethrough which help to atomize the fluid upon discharge therethrough. The director plate may additionally include channels of various shapes which help to introduce turbulence which promotes atomization. One such fluid injector with a director plate is shown in U.S. Pat. No. 6,186,421 to Wahba et al., the disclosure of which is hereby incorporated by reference in its entirety. While known director plates help to atomize the fluid, improvements are continually sought to obtain greater degrees of atomization.
What is needed is a fluid injector which minimizes or eliminates one or more of the shortcomings as set forth above.